1. Field of the Invention
The invention relates to a ground working implement, particularly for underground working, having, a slide displaceable relative to a base by means of a lifting cylinder arrangement, which is on the one hand connected to the slide and on the other to the base and has two oppositely acting lifting cylinder devices.
2. Description of the Related Art
DE-A-195 14 288 e.g. discloses a drilling implement of the aforementioned type. Said drilling implement has a bilaterally acting hydraulic cylinder for the linear displacement of a drilling drive. Such a tandem cylinder has a through cylinder casing, a lifting piston being extendible from either side. Compared with a single-acting lifting cylinder said tandem cylinder has the advantage of a better flexural stiffness of the lifting piston to be extended as a result of the reduced length of the two lifting pistons to be extended.
As with a single-acting cylinder, in the case of the tandem cylinder the maximum lift length corresponds to the installation or laid length of the lifting cylinder means and as a result the lift height is limited.
JP-A-09078971 discloses a ground working implement with an oppositely acting lifting cylinder arrangement. Two lateral, single-acting lifting cylinders are arranged in offset, displaceable manner with respect to a tandem cylinder. Also with this known lifting cylinder arrangement the maximum lift length is roughly limited to the installation length of the tandem cylinder.
Finally, DE-A-28 17 017 discloses a horizontal press drilling tool, in which a soil auger can be pressed into the soil by means of two main hydraulic cylinders. There are also two auxiliary cylinders, whose lifting pistons are connected to the cylinder casings of the main cylinders so as in this way to achieve an independent movement of the soil auger with respect to a drill tube. Also in this arrangement the maximum lift length is roughly limited to the installation length of the main cylinders.